There are a range of external ear abnormalities relate to final structure, size and position. In some cases these abnormalities relate directly to pharyngeal arch development or may be part of a wider spectrum of abnormalities associated with a genetic or environmental (fetal alcohol syndrome) disorders. Some known abnormalities include: anotia, microtia, prominent ear, lop ear, cup ear, cryptotia and Stahl's ear. Other associated external ear abnormalities include the formation of the external auditory meatus (canal) and pre-auricular fistulae (pits) and appendages.

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There are a range of external ear abnormalities relate to final structure, size and position. In some cases these abnormalities relate directly to pharyngeal arch development or may be part of a wider spectrum of abnormalities associated with a genetic or environmental (fetal alcohol syndrome) disorders. Some known abnormalities include: anotia, microtia, prominent ear, lop ear, cup ear, cryptotia and Stahl's ear. Other associated external ear abnormalities include the formation of the external auditory meatus (canal) and pre-auricular fistulae (pits) and appendages. Finally, a range of abnormalities can be found associated with the overlying skin of both the external ear and the ear canal.

Some Recent Findings

Pinna- Auricle

Embryonic External Ear

Images of the lateral view of the human embryonic head from week 5 (stage 14) through to week 8 (stage 23) showing development of the auricular hillocks that will form the external ear. The adult ear is also shown indicating the part of the ear that each hillock contributes.

develops from six aural hillocks: 3 on first pharyngeal arch and 3 on the second pharyngeal arch.

Meatal plug extends in a disc-like fashion. In the horizontal plane the meatus is boot-shaped with a narrow neck and the sole of the meatal plug spreading widely to form the future tympanic membrane medially. Proximal portion of the neck starts to be resorbed.

13 weeks

Disc-like plug innermost surface in contact with the primordial malleus, contributes to the formation of the tympanic membrane.

16.5 week

Meatus is fully patent throughout its length, lumen is still narrow and curved.

18 week

Meatus is already fully expanded to its complete form.

(Nishimura, 1992}

External Auditory Meatus

External auditory meatus and the outer ear.

Innervation

The auriculotemporal nerve supplies a large part of the pinna, some innervation may also arise from the trigeminus.

Molecular

Outer Ear Genes

controlled by genes that regulate arch 1 and 2 development

related to hindbrain segmentation (rhombomere 4)

Mouse - Hox a1/Hoxb1, goosecoid, Endothelin1, dHAND

Abnormalities

There are a range of external ear abnormalities relate to final structure, size and position. In some cases these abnormalities relate directly to pharyngeal arch development or may be part of a wider spectrum of abnormalities associated with a genetic or environmental (fetal alcohol syndrome) disorders. Some known abnormalities include: anotia, microtia, prominent ear, lop ear, cup ear, cryptotia and Stahl's ear. Other associated external ear abnormalities include the formation of the external auditory meatus (canal) and pre-auricular fistulae (pits) and appendages. Finally, a range of abnormalities can be found associated with the overlying skin of both the external ear and the ear canal.

Anotia

Upper Auricular Detachment

Microtia

Cleft Lobule

Stahl's Ear

A rare ear abnormality, where the rim of the ear is flattened and the upper portions deformed. More common in Oriental background and can occur from mild to severe. The skin and cartilage are both folded to different degrees that can result in a pointed upper edge. This pointed ear has been said to resemble the Star Trek television character "Vulcan" ear shape.

External Auditory Meatus

The external auditory meatus (canal) can also fail to canalise leading to a range of malformation including membranous and/or bony atresia and stenosis.